Abstract: Low side lobe array antenna is a common requirement of modern radar, but the pattern of low side lobe antennas are usually influenced by random errors, if not fully consider the effect of random errors during design, random errors will bring great impact on the actual results. To solve the above-mentioned problem, a method suitable for the random error analysis of low side lobe beam formed by radar array antenna is presented in this paper, by which the reasonable side lobe level in the Taylor synthesis for low side lobe beam and the amplitude and phase errors can be determined. Moreover, the effects of the random errors on the array direction and beam direction of array are analyzed. Simulated results are given and found this method to be valid.